Apparatus and process for the manufacture of zinc dust



July 2, 1935. 'F w, SCHULZE 2,007,027

APPARATUS AND PROCESS FOR THE MANUFACTURE OF ZINC DUST Filed May 51,1954 INVENTOR.

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Patented July 2, 193E;v

UNITED STATES .PATENTAI OFFICE" i This invention relates to a processand apparatus for the manufacture of zincjdust, and is particularlydirected to processes and apparatus wherein two retorts and twocondensers are interconnected whereby on the cessation of operation .ofone retort the temperature of the gases in its condenser is maintainedand the contraction of the gases in the condenser prevented. In'themanufacture of zinc dust it iscustomary to charge zinc, 'or'zinccontaining material, into a retort wherein the zinc is vaporized. Thezinc vapors are then led into a condenser where they are cooled to formzinc dust.

The temperature of gases in the condenser is, naturally, rather high andwhen the charge of zinc is exhausted and the zinc vapors are no longerdischarged into the condenser the temperature of the gases in thecondenser drops. As soon as the charge of zinc is exhausted it isnecessary to supply more zinc to the retort, and to do this the retortis opened. As the gases in the condenser .cool they naturally diminishin volume with the result that, while the retort is open, air is suckedinto the condenser to make up for the decrease in volume of the gases inthe condenser. When the retort is again started up the first zinc vaporsled into the condenser react with the" air therein to form zinc oxide,and the zinc ,dust contains an undesirable amount of zinc oxide.

It has been proposed to provide an expansible breather into which thegases could expand while hot, and, on the cooling of the gases, theexpansible breather would diminish in size with-- the contraction of thegases. This, however, requires the installation of extra apparatus witha corresponding increase in'costs.

It is an object of my invention to prevent the drawing of 'air into acondenser while its retort is not operating without the use of extraapparatus and at a negligible cost. It is a further object 01' myinvention to provide a process and apparatus with which zinc dust verylow in zinc oxide can be made. A still further object of my invention isto provide a means of using existing zinc dust. manufacturing equipmentwith a minimum amount of modification. Further objects will appear asthe description of my invention proceeds.

My invention contemplates interconnecting'adjacent condensers withasuitable pipe. This is easily done, for in most cases theretort-condenser units are set in pairs so that one worker can care fortwo such units. Suitable valves are provided so that if one retort is tobe subjected to lengthy repairs it can be isolated from the otherretortcondenser unit. Obviously more than two retortcondenser units canbe similarly interconnected ii desired. 4

In the accompanying drawing there is shown illustrative apparatus forthe practice of my inv vention: V

Figure 1 shows a pair of retort-condenser units modifiedaccording'to'the preferred manner of my invention Figure 2 shows aslightly modified form of-my invention. g

In Figure 1 there are shown condensers l and 2 each communicating withretorts 3, 3. At the lower end of each condenser there is provided asuitable valve 6 and zinc dust receptacle l. The specific constructionof the retorts, retort heating 13 means, condensers, etc., forms no.esential part of my invention, and may be oi-anydesired type.

The units'illustrated in the drawing are of the type shown and claimedin-U. S. Patent 1,762,716, to H. A. Grine.

According to my invention a pipe 8 extends from the top of condenser lto the top of condenser 2. A suitable valve 1 is interposed in pipel. fIn the operation of theembodiment-"of Figure 25 1, both retorts are setin operation in the usual way. Now, assuming that the retort ofcondenser vl needs recharging, the valve 1 is opened "and theretbrtopened and charged as quickly as possible. During the charging ofthe retort zinc 30 vapor, hot zinc dust, and a slight amount of hotgases pass from condenser 2 into condenser I and maintain the gasestherein at practically operating temperature. No undue amount of air,therefore, is drawn into condenser i and, as soon 35 as the retort ischarged and started operating, the zinc dust formed in condenser. l issubstantiallyfree of zinc oxide. A, similar procedure is followed whenthe retort of condenser 2 needs recharging. p

The valve 1 is open during recharging and it maybe closed, if desired,between such recharging periods. It is not necessary, of course, toclose it during normal operation. If one of the retorts or condensersneeds repairs, .or is for any 45 other reason to be out of use for aconsiderable period, the valve I may be closed and the other"retort-condenser unit operated alone.

In the modification of Figure 2 there'is seen an apparatus like that ofFigure 1, except that 50 valves 8 and I 0 are provided between the re-xtorts oi condenser I and 2 respectively. When a; retort is beingrecharged the valve between it and its-condenser may be closed to moreefiectively prevent access of air to its condenser. The

gases in the condenser are maintained at substantially the operatingtemperature by the pipe 8. If the pipe 8 were not provided, the coolingof the gases in the condenser would cause the infiltration of air, orfailing that, the collapse of the condenser. The valve 1 is used as inthe embodiment of Figure 1, but it may be omitted if desired. I do notprefer the modification of Figure 2, as it is very desirable to have theline he tween the retort and condenser as short as possible and theinsertion of a valve necessarily lengthens it. Also, the valves and Mare subject to very high temperatures, while valve I is subjected tomuch lower temperatures.

While I have shown specific forms of apparatus above, I do not intend tobe limited thereby, the scope of my invention being set forth in theappended claims.

I claim:

1. In a process for the manufacture of zinc dust, the step comprisingmaintaining the gases in a condenser near normal operating temperatureswhile a retort which communicates with the condenser is not operating.

2. In a process for the manufacture of zinc dust in an apparatuscomprising a retort and communicating condenser, the step comprisingsupplying hot inert gases, zinc vapor, and hot zinc dust to thecondenser while the retort is not in operation whereby the gases inthecondenser are maintained near normal operating temperatures.

3. In a processior the manufacture of zinc dust in an apparatuscomprising two retortcondenser units, the steps comprising leading hotzinc dust and zinc vapors from one condenser to a second condenser whenthe retort which normally discharges zinc vapor into said secondcondenser is not in operation.

4. An apparatus for the manufacture of zinc dust comprising tworetort-condenser units and means for permitting the passage of zincvapors from one condenser to the other.

5. An apparatus for the manufacture of zinc dust comprising a retort, acondenser communicating therewith, a second retort and condenser, apassage from one condenser to the other providing communication betweenthe retorts, and

valve means for interrupting the communication between the retorts.

6. An apparatus for the manufacture of zinc dust comprising a retort, acondenser communicating therewith, a second retort with a secondcondenser communicating therewith, a pipe connected to each of the saidcondensers providing communication therebetween, and valve means in thepipe,

7. An apparatus for the manufacture of zinc dust comprising a retort, acondenser communicating therewith, a'second retort with a condensercommunicating therewith, means providing communication between the twocondensers, and valve means between each retort and condenser forinterrupting communication therebetween.

JOHN F. W. SCHULZE.

